The present invention relates to a connecting system for a gas-insulated switchgear apparatus, or more in particular to a construction in which the connecting system is arranged on the side of an electrical device installed adjacently to the gas-insulated switch-gear apparatus.
Generally, in a power generation plant or a power substation, gas-insulated devices such as a gas-insulated switchgear apparatus of respective phases including a gas-insulated circuit breaker and a disconnector are installed on one side of a partition wall or within a building at a predetermined place of installation, and an electrical device such as a transformer or a reactor is arranged adjacently to such gas-insulated devices. Each of the gas-insulated devices of respective phases, on the other hand, is provided with a bushing for connection with a transmission line or other electrical devices through a connection cable. This bushing, for convenience of external connection or installation of the electrical device, is sometimes arranged unavoidably on the other side of the gas-insulated devices opposite to the electrical device side, that is, on the installation side of the electrical device. In such a case, gas-insulated bus bars used for connection between the gas-insulated devices of respective phases and the bushings are laid in according to a selected one of the methods mentioned below. A first method is for the bus bars to circumvent the electrical device installed on a foundation, and a second method is by laying the bus bars through the foundation part of the installed electrical device. The first method of laying the bus bars, in which the gas-insulated bus bars circumvent the electrical device, has the disadvantage of a great length over which the bus bars are laid. In the second method, in contrast, the mechanical strength of the foundation of the electrical device is required to be increased on the one hand, and small-size bus bar units split up are connected as it is impossible to lay integrated gas-insulated bus bars through the foundation, thereby making it necessary to enlarge the working underground pit on the other hand. To increase the strength of the foundation of a heavy-duty electrical device while realizing such a spatial need at the same time, however, is practically impossible.
To solve this problem, a suggestion has so far been made of a method to lay gas-insulated bus bars connecting the gas-insulated devices and bushings without affecting the installation of the electrical device.
U.S. Pat. No. 3,639,673 is well known for its disclosure of an example of laying gas-insulated bus bars in the ground. Japanese Utility Model Unexamined Publication No. 70015/83, on the other hand, discloses a method in which gas-insulated devices arranged in a building and an electrical device installed outside of the building are connected by gas-insulated bus bars laid in a pit formed in the ground. Further, a support construction for the bushing generally used with a gas-insulated device is disclosed in Japanese Utility Model Unexamined Publication No. 2711/81.